Why Red Light Therapy Could Be Sabotaging Sperm Health

You’ve seen the Instagram reels. You’ve heard the podcasts. Everyone from your crunchy neighbor to your biohacking brother-in-law is raving about red light therapy. And honestly? I’m right there with them, from clinical and personal experience.

When it comes to sperm health, that boost of energy translates to better motility, stronger swimmers, and a higher chance of successful conception. But if you’re trying to improve sperm health there’s one very important detail we have to address.

The Red Light You’re Using Might Be Doing More Harm Than Good

So here’s the scoop: not all red light wavelengths have the same effect on sperm. A brand new 2025 study looked at five different types of light - 450, 635, 810, 940, and 1064 nm (in vitro) on sperm from men with poor motility (asthenozoospermia).

And guess what they found?

635 nm - one of the most common red light wavelengths,was the worst performer.

In fact, it consistently made sperm worse.

It decreased energy production (ATP).
It increased energy stress (AMP).
It caused a surge in nitric oxide, which sounds good… until it’s not.

Isn’t Nitric Oxide Supposed to Be Helpful?

Yes. And no.

At just the right level, NO helps sperm move and function. But too much of it? It actually disrupts mitochondrial function, the exact thing red light is supposed to help.

In this study, 635 nm caused a huge spike in nitric oxide, way more than other wavelengths like 810 or 1064 nm.

Result? Less energy. Less motility. Not exactly what you want when trying to conceive.

810 nm for the Win

If you’re using red light for male fertility, the hero of the story is 810 nm.

In the same study:

It boosted ATP (cell energy) production.
It didn’t overstimulate nitric oxide.
And most importantly, it kept sperm safe, there were no signs of DNA or membrane damage.

What This Means for You (and Your Man)

If you’re using a red light device that uses 635 nm and you’re TTC you might want to stop - or turn off that wavelength if you can.

Take a deep breath - the study showed that 635 nm reduced ATP, but did not cause DNA or membrane damage. That means if you've been using a red light device with 635 nm, it likely didn’t harm your sperm permanently. Once exposure stops, your sperm will be replaced with new ones in about 72 days.

Skip the cheap Amazon products. They're often heavy on 635 nm and light on science. If your goal is conception, not just anti-aging, you need clinical-grade, 3rd party tested specs.

If you’re working with a clinic, ask about their settings. Don’t assume that all red light treatments are helpful. Dose, wavelength, and timing all matter. Red light therapy can be an incredible tool on your fertility journey, but only if you’re using the right kind of light.

My recommended PBM devices (most red light torches don’t allow you to switch off the red light and just use the NIR). The Novaalab pad can be used for male and female fertility and allows for NIR only, both and has pulsing mode.

Tracy

https://blog.tracydonegan.org/blog/boost-sperm-health-with-red-light-therapy

Resources:

Balbi M, Lai R, Stigliani S, Massarotti C, Bozzo M, Scaruffi P, Ravera S, Amaroli A. Efficacy and Safety of Visible and Near-Infrared Photobiomodulation Therapy on Astenospermic Human Sperm: Wavelength-Dependent Regulation of Nitric Oxide Levels and Mitochondrial Energetics. Biology. 2025; 14(5):491.